Certain medical procedures require the heart or lung of a patient to be kept still. This may be necessary in order for a surgeon to perform surgical procedures, such as cardiac surgery. While the heart is unable to circulate blood or the lung is unable to re-oxygenate blood or to remove carbon dioxide, heart-lung machines are used for life support, providing extracorporeal oxygenation to maintain a supply of oxygen to a patient.
More recently, extracorporeal oxygenation has been explored for the management of viral infections (such as H1N1) that affect lung function by causing pulmonary embolisms. Patients suffering from such infections may require long-term ventilation, in the region of several weeks (typically 20 days, but in severe cases ventilation may be required for several months, e.g. for up to 180 days), in order to facilitate treatment and drainage of the lung, and in order to permit the lung to rest and heal while the patient's immune system is given an opportunity to defeat the viral infection.
The partial pressures of oxygen and carbon dioxide, pO2 and pCO2, are indicative of physiological activity and, thus, of interest for extracorporeal oxygenation management. PCT-published application WO2012066280 by the present applicant discloses a method and apparatus for determining pO2 and/or pCO2 as a function of, inter alia, the amount of carbon dioxide CO2 entering and exiting a ventilation machine. United Kingdom patent application number GB1503805.2 by the present applicant describes methods and apparatus for determining the partial pressure of oxygen pO2 as a function of, inter alia, the oxygen uptake in an oxygenator.
The present invention seeks to provide improved options for ventilation management.